CBSE Class 5 Science Lesson Natural Disasters

Types of Natural Disasters

1. Earthquakes
2. Floods
3. Cyclone
4. Tsunami
5. Tidal Waves
6. Droughts

Key Points

1. Natural Disasters - A nature's fury that may destroy a part of our life and property or may result in death and destruction of the property.
E.g. earthquakes, droughts, floods, tsunamis etc.

2. Earthquakes - A sudden shaking of a part of the Earth's surface (ground) caused by movements or vibrations deep inside the Earth.

3. Seismograph - An instrument used to measure the intensity, direction and duration of an earthquake.

4. Richter Scale - The scale that measures the magnitude of an earthquake.

5. Famine - Lack of food for a long period of time in a region caused due to drought.

6. Cyclone - A violent circular wind accompanied with heavy rains.

7. Floods - The overflowing of river waters that results in submerging of nearby areas.

Question and Answers

1. Q. How do earthquakes affect the Earth and its people?
   Ans. Effects of Earthquake:
   • Earthquakes of high intensity cause massive destruction.
   • Buildings collapse, roads and bridges get damaged and trees get uprooted.
   • Sometimes fires break out due to the damage of electric wires.
   • It can cause landslides that disrupt the transport and communication system.


2. Q. What are the damages caused by a flood?
   Ans. Floods damage crops, submerge houses, roads and destroy property. Animals living in the soil like snakes, rats and earthworms die due to water logging caused by floods. Water supply, communication network and electric lines get affected by floods.


3. Q. What is tsunami? How is it caused and how does it effect human life?
   Ans. Tidal waves or storm waves are known as tsunami. It is a Japanese word which means 'harbour waves'. Tsunami is caused by undersea earthquakes or by severe cyclones. It causes destruction on the shore within seconds. The giant waves travel at a speed of 800 Km per hour and cause severe damage to buildings, uproot trees and wash away people and animals.


4. Q. What is drought? List out the conditions that cause drought.
   Ans. When a particular area has no rain or very less rain than the normal rainfall for a long period of time it causes drought. Drought is caused due to hot and dry winds, lack of rainfall, very high temperature and evaporation of moisture from the ground.


5. Q. We generally hear about epidemics after any natural disaster. Why?
   Ans. An epidemic is an outbreak of a communicable disease that spreads rapidly to a human population. Factors for epidemic after a natural disaster are:
   
   1. Population displacement
   2. Lack of safe water
   3. Lack of sanitation facilities
   4. Lack of health care services
   


6. Q. How do people suffer in drought affected areas?
   Ans. People in drought affected areas do not get food and water. There will be severe shortage of water as the nearby ponds and lakes dry up and crops dry up due to huge cracks formed in the soil. The main reason for drought are large scale cutting of trees, clearing of forests for the development of towns and cities and overgrazing by the cattle.


7. Q. Sometimes earthquakes cause fire. Why?
   Ans. Fire is one of the major hazard caused due to earthquake. It can be caused by tipped over power lines and gas lines or by stoves that use wood or coal.


8. Q. In coastal areas flooding is often caused by cyclones. How?
   Ans. A cyclone is a very strong wind accompanied with heavy rains. Strong winds cause destruction on land and high waves in the sea causes floods. So in coastal areas flooding is often caused by cyclones.